With most recent advancement in semiconductor device manufacturing, field-effect-transistors with self-aligned contact-to-diffusion are generally viewed as a necessity for 14-nm node and beyond in order to enable gate pitch scaling with further dense integration of semiconductor devices.
In the meantime, replacement-gate (“gate-last”) technologies such as, for example, replacement-metal-gate (RMG) technologies are current front-runners and choice of manufacturing for the 14-nm node. However, replacement-gate technologies tend to be much less amendable to self-aligned contacts (“SAC”) because an insulating cap is generally required to be self-aligned atop the conductive gate electrode such that the gate does not get shorted to the self-aligned contact. In addition, etch-back and planarization schemes that are necessary to make the RMG structure generally have small margins of manufacturing.